A lead-acid battery disclosed in JP-A-2011-134587 includes a metal-made terminal member which is formed in a resin-made cover for closing a container by insert molding. The terminal member includes: a terminal portion to which an external line is connected; and a cylindrical bushing into which poles extending from an electrode group arranged in the container are inserted and to which the poles are welded.
It is often the case where a space for housing a lead-acid battery mounted on a vehicle or the like is limited to a narrow space. Recently, for enhancing performance of a lead-acid battery in the narrow space or for realizing the further miniaturization of the lead-acid battery, there has been made an attempt to shorten a length of the bushing in the cylinder axis direction in order to increase a rate that constitutional members such as electrode plates occupy in the lead-acid battery. Although the bushing is embedded in a resin material which forms the cover, the shorter the length of the bushing, the shorter a creeping distance of a portion where an outer peripheral surface of the bushing and the cover face each other in an opposed manner becomes so that an electrolyte solution in the container tends to climb up through a minute air gap between the outer peripheral surface of the bushing and the cover and exudes. Further, when the electrolyte solution exudes to a terminal portion, the electrolyte solution spreads over and wets the whole terminal portion thus becoming a cause of a color change or the like.